<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div class="box">2222</div>
<ul>
  <li></li>
  <li></li>
  <li></li>
</ul>

  <script>
    const box = document.querySelector('.box')
    box.innerHTML = '我是'
    
    const lis = document.querySelectorAll('ul li')
    for(let i = 0 ; i < lis.length ; i++){
      console.log(lis[i])
    }
    console.log(lis)
    console.log(box)
  </script>
</body>
</html>